Discrete subaortic stenosis: assessing adequacy of myectomy by transesophageal echocardiography

Membranectomy and myectomy are standard therapy for discrete subaortic stenosis (DS) and are associated with low rates of endocarditis, recurrence, and aortic insufficiency. Extensive myectomy increases risk of complications such as conduction tissue damage and iatrogenic ventricular septal defect (VSD).

Forty-five adult patients with DS underwent operations in Gulhane Military Medical Academy. Exertional dyspnea was the principal symptom in 29 (64.4%) patients. Transesophageal echocardiography (TEE) was performed routinely in all patients to assess the length and depth of needed myectomy during the perioperative period. Aortic insufficiency (AI) was also noted preoperatively in 31 (68.9%) and a history of aortic valve endocarditis was present in 4 (8.9%) patients.

Myectomy was performed according to TEE measurements. An average of 10 mm in width, 10 mm in depth, and 2.3 mm in length of septal tissue was resected. The mean left ventricle-aorta peak systolic gradient decreased from 70.2+/-9.7 to 17.2+/-2.7 mmHg (p < 0.001). Aortic valve repair was performed in 8 (7.8%) patients and aortic valve replacement in 11 (24.4%) patients at the initial operation. Iatrogenic VSD did not occur in any of the patients. Average postoperative left ventricular outflow tract diameter was 21+/-1.5 mm. Temporary complete heart block occurred in three patients. There was an early residual gradient (36+/-8 mmHg) resulting from temporary hypercontraction that decreased (18+/-5 mmHg) in the first postoperative day.

Myectomy under perioperative TEE measurement is safe and effective in the treatment of DS. TEE-guided myectomy reduces complications such as complete heart block and iatrogenic VSD.